Study is ‘all based on analyses of 73 samples of deep-ocean sediments, corals, shells, etc.’
The four authors, three from OSU and one from Harvard, are quite fuzzy in defining the word “recent.” Their analysis takes 1950 as “present.” But then they add a humongous temperature increase by using all of the 20th century. That’s really the crux of their claim, but also their weakest point: The only warming that’s sure is from 1910 to 1940. Although that warming is certainly genuine, only a few fanatic scientists believe that it is human-caused. Not even the IPCC considers the warming up to 1940 as anthropogenic.
On the other hand, the large surface warming claimed from 1979 to 2000 may not even exist. Opinions are divided on this important question. The warming is certainly not seen in the satellite data, the best global temperature observations we have.
Of course, the authors ignore the fact that there has been no warming for at least a decade – while anthropogenic greenhouse gases have been increasing more rapidly. According to Philip Jones, the IPCC’s guru on Global Temperatures, there hasn’t been any significant global warming for 17 years!
Even stranger is their forecast for the future — entirely based on climate models that have never been validated. Their exact quote is: “By 2100, global average temperatures will probably [be] 5 to 12 sigma deviations above the Holocene temperature mean.” In non-technical language, this means a huge increase; but the probability of a large temperature rise is practically nil. Of course, they leave themselves plenty of room by providing at least half a dozen projections depending on assumed scenarios.
Hiding the data mix
What is distinctive about this latest effort at claiming unusual 20th-century warming and implying a human contribution is their presentation. The original hockey stick, first published in 1998, explained carefully that the modern instrumental (thermometer) record had been grafted onto a centuries-long proxy (non-thermometer) record; the OSU paper neglects to inform the reader about this important fact.